Using enclosing function's type parameter in enum definition yields ICE instead of error

[jld]

fn f<T>() { enum E { V(T) } }
pub fn main() { f::<int>(); }

⇒ error: internal compiler error: fictitious type ty_param({idx: 0, def_id: {crate: 0, node: 1}}) in sizing_type_of()

fn f<T>() { struct S(T); }
pub fn main() { f::<int>(); }

⇒ error: attempt to use a type argument out of scope

[metajack]

This still happens on today's master.

Nominating for production ready.

[nikomatsakis]

To be clear: I think the expected behavior here is an error
because the T is not in scope for nested items. So the
code ought to be enum<T> { Foo(T) } (similar to how a nested
fn couldn't reference T)

[graydon]

just a bug, removing milestone/nomination.

[huonw]

Triage, we're still creating types that are apparently fictitious and crashing.

[flaper87]

This no longer ICE, it now outputs an error: error: missing type param T in the substitution of T

Adding the type parameter to the enum succeeds. Flagging as needs test.